Method for making inkjet-printed encapsulated quantum dots, light conversion unit, and micro LED display panel

1. A method for making inkjet-printed encapsulated quantum dots, comprising steps of: providing a substrate having a hydrophobic surface and a quantum dots (QDs) solution comprising at least one quantum dot (QD), a water solvent and a solute having a cohesion force; using an inkjet-printing nozzle to carry out an inkjet printing of the QDs solution on the hydrophobic surface of the substrate, such that a droplet of the QDs solution is formed on the hydrophobic surface; and applying a drying process to the droplet of the QDs solution, so as to make a volume of the droplet shrink with an increase of a drying time, thereby forming a micro encapsulated QD structure on the substrate.

2. The method of claim 1 , wherein the micro encapsulated QD structure comprises an encapsulation body that is formed by the solute and at least one QD that is enclosed in the encapsulation body.

3. The method of claim 1 , wherein the solute has a concentration in a range between 0.5 wt % and 5.5 wt %, and being made of a material that is selected from the group consisting of LiCl, NaCl, KCl, LiI, NaI, KI, LiBr, NaBr, an KBr.

4. The method of claim 1 , wherein a surfactant is further added into the QDs solution, so as to effectively reduce a formation of at least one satellite droplets in case of the droplet of the QDs solution is dropped onto the hydrophobic surface of the substrate through the inkjet-printing nozzle.

5. The method of claim 1 , wherein the QD has a hydrophilic layer that is formed by applying a surface modification process to the QD, and the QD is selected from the group consisting of red QD, green QD and blue QD.

6. A light conversion unit, comprising: a transparent substrate; a light convertor carrying layer, being formed on a top surface of the transparent substrate, and being made of a metal material or a metal oxide material; a plurality of first through holes, being formed on the light convertor carrying layer, and being arranged to M/3 rows and M/3 columns, wherein each of the plurality of first through holes form a first accommodating groove in combination with the top surface of the transparent substrate; a plurality of second through holes, being formed on the light convertor carrying layer, and being arranged to M/3 rows and M/3 columns, wherein each of the plurality of second through holes form a second accommodating groove in combination with the top surface of the transparent substrate; a plurality of third through holes, being formed on the light convertor carrying layer, and being arranged to M/3 rows and M/3 columns, wherein each of the plurality of third through holes form a third accommodating groove in combination with the top surface of the transparent substrate; a first quantum dots (QDs) solution, comprising at least one red quantum dot (QD), a water solvent and a first solute having a cohesion force, wherein the first QDs solution is dropped into each of the first accommodating grooves by using an inkjet-printing nozzle, so as to form a first droplet in each of the first accommodating grooves; and a second QDs solution, comprising at least one green QD, the water solvent and a second solute having the cohesion force, wherein the second QDs solution is dropped into each of the second accommodating grooves by using the inkjet-printing nozzle, so as to form a second droplet in each of the second accommodating grooves; wherein in case of letting the top surface of the substrate be a hydrophobic surface so as to make the cohesion force of the first solute and the cohesion force of the second solute be both greater than a driving force for impelling outward-bound flow that is induced by a coffee ring effect, the first droplet and the second droplet being eventually converted to a first micro encapsulated QD structure and a second micro encapsulated QD structure after applying a drying process to the first droplet and the second droplet, thereby making each of the first accommodating grooves have the first micro encapsulated QD structure therein, and simultaneously making each of the second accommodating grooves have the second micro encapsulated QD structure therein; wherein M and N are both a positive integer.

7. The light conversion unit of claim 6 , further comprising a third QDs solution that comprises at least one blue QD, the water solvent and a third solute having the cohesion force, wherein the third QDs solution is dropped into each of the third accommodating grooves by using the inkjet-printing nozzle, so as to form a third droplet in each of the third accommodating grooves; wherein the third droplet is eventually converted to a third micro encapsulated QD structure after applying the drying process to the third droplet, thereby making each of the third accommodating grooves have the third micro encapsulated QD structure therein.

8. The light conversion unit of claim 7 , wherein the first micro encapsulated QD structure comprises a first encapsulation body that is formed by the first solute and at least one red QD that is enclosed in the first encapsulation body, the second micro encapsulated QD structure comprising a second encapsulation body that is formed by the second solute and at least one green QD that is enclosed in the second encapsulation body, and the third micro encapsulated QD structure comprising a third encapsulation body that is formed by the third solute and at least one blue QD that is enclosed in the third encapsulation body.

9. The light conversion unit of claim 7 , further comprising: an encapsulation material, being filled into each of the first accommodating grooves, each of the second accommodating grooves and each of the third accommodating grooves, so as to enclose the first micro encapsulated QD structure, the second micro encapsulated QD structure and the third micro encapsulated QD structure in the first accommodating groove, the second accommodating groove and the third accommodating groove, respectively; and a barrier layer, being disposed on the light convertor carrying layer for covering all the first accommodating grooves, the second accommodating grooves and the third accommodating grooves, and being used for blocking moisture and oxygen.

10. The light conversion unit of claim 6 , wherein the metal material is selected from the group consisting of gold (Au), copper (Cu), aluminum (Al), silver (Ag), chromium (Cr), molybdenum (Mo), titanium (Ti), indium (In), antimony (Sb), and alloy comprising two or more of the forgoing metal materials.

11. The light conversion unit of claim 6 , wherein the metal oxide material is selected from the group consisting of copper oxide, aluminum oxide, silver oxide, chromium oxide, molybdenum oxide, titanium oxide, indium oxide, antimony oxide, and compound comprising two or more of the forgoing metal oxide materials.

12. The light conversion unit of claim 6 , wherein the first solute, the second solute and the third solute are all selected from the group consisting of LiCl, NaCl, KCl, LiI, NaI, KI, LiBr, NaBr, and KBr.

13. The light conversion unit of claim 6 , wherein a surfactant is further added into the first QDs solution, the second QDs solution and the third QDs solution, so as to effectively reduce a formation of at least one satellite droplet in case of the first droplet, the second droplet and the third droplet are injected by the inkjet-printing nozzle.

14. The light conversion unit of claim 6 , wherein the red QD, the green QD and the blue QD are all provided with a surface hydrophilic layer after a surface modification process is applied to the red QD, the green QD and the blue QD, and the first solute, the second solute and the third solute all having a concentration in a range between 0.5 wt % and 5.5 wt %.

15. A micro LED display panel, comprising: a substrate; M×N micro LED components, being disposed on the substrate; a transparent substrate, being disposed on the substrate and the M×N micro LED components; a light convertor carrying layer, being formed on a top surface of the transparent substrate, and being made of a metal material or a metal oxide material; a plurality of first through holes, being formed on the light convertor carrying layer, and being arranged to M/3 rows and M/3 columns, wherein each of the plurality of first through holes form a first accommodating groove in combination with the top surface of the transparent substrate; a plurality of second through holes, being formed on the light convertor carrying layer, and being arranged to M/3 rows and M/3 columns, wherein each of the plurality of second through holes form a second accommodating groove in combination with the top surface of the transparent substrate; a plurality of third through holes, being formed on the light convertor carrying layer, and being arranged to M/3 rows and M/3 columns, wherein each of the plurality of third through holes form a third accommodating groove in combination with the top surface of the transparent substrate; a first quantum dots (QDs) solution, comprising at least one red quantum dot (QD), a water solvent and a first solute having a cohesion force, wherein the first QDs solution is dropped into each of the first accommodating grooves by using an inkjet-printing nozzle, so as to form a first droplet in each of the first accommodating grooves; and a second QDs solution, comprising at least one green QD, the water solvent and a second solute having the cohesion force, wherein the second QDs solution is dropped into each of the second accommodating grooves by using the inkjet-printing nozzle, so as to form a second droplet in each of the second accommodating grooves; wherein in case of letting the top surface of the substrate be a hydrophobic surface so as to make the cohesion force of the first solute and the cohesion force of the second solute be both greater than a driving force for impelling outward-bound flow that is induced by a coffee ring effect, the first droplet and the second droplet being eventually converted to a first micro encapsulated QD structure and a second micro encapsulated QD structure after applying a drying process to the first droplet and the second droplet, thereby making each of the first accommodating grooves have the first micro encapsulated QD structure therein, and simultaneously making each of the second accommodating grooves have the second micro encapsulated QD structure therein; wherein M and N are both a positive integer.

16. The micro LED display panel of claim 15 , further comprising a third QDs solution that comprises at least one blue QD, the water solvent and a third solute having the cohesion force, wherein the third QDs solution is dropped into each of the third accommodating grooves by using the inkjet-printing nozzle, so as to form a third droplet in each of the third accommodating grooves; wherein the third droplet is eventually converted to a third micro encapsulated QD structure after applying the drying process to the third droplet, thereby making each of the third accommodating grooves have the third micro encapsulated QD structure therein.

17. The micro LED display panel of claim 16 , wherein the first micro encapsulated QD structure comprises a first encapsulation body that is formed by the first solute and at least one red QD that is enclosed in the first encapsulation body, the second micro encapsulated QD structure comprising a second encapsulation body that is formed by the second solute and at least one green QD that is enclosed in the second encapsulation body, and the third micro encapsulated QD structure comprising a third encapsulation body that is formed by the third solute and at least one blue QD that is enclosed in the third encapsulation body.

18. The micro LED display panel of claim 16 , wherein the first solute, the second solute and the third solute are all selected from the group consisting of LiCl, NaCl, KCl, LiI, NaI, KI, LiBr, NaBr, and KBr.

19. The micro LED display panel of claim of claim 16 , wherein the red QD, the green QD and the blue QD are all provided with a surface hydrophilic layer after a surface modification process is applied to the red QD, the green QD and the blue QD, and the first solute, the second solute and the third solute all having a concentration in a range between 0.5 wt % and 5.5 wt %.

20. The micro LED display panel of claim 16 , wherein a surfactant is further added into the first QDs solution, the second QDs solution and the third QDs solution, so as to effectively reduce a formation of at least one satellite droplet in case of the first droplet, the second droplet and the third droplet are injected by the inkjet-printing nozzle.